The hydrogen washout technique and a simplified microangiographic technique will be used to study the hemodynamics of the femoral head. The contributions of subsynovial vessels and vessels crossing the old epiphyseal scar will be compared in the normal state and in degenerative arthrosis and inflammatory arthritis. The effect of surgical dissection on femoral head and neck circulation in normal and pathological states will also be determined using hydrogen washout and microangiographic techniques. The long-term effect of inflammatory arthritis on intracapsular pressure, and the resulting effect on the circulation to the femoral head will be studied with a combination of hydrogen washout and angiography. Viability of the cells will be assesed after prolonged elevation of intracapsular pressure to a level comparable to that encountered in inflammatory disease of the hip.